Suppose I am working at the C-- level. Is it valid to do:

set_field (Cconst_symbol some_sym) 0 some_word

under the assumption that some_symbol is a label in the data section of the
current compilation unit?  or is the compilation unit's data (emitted via
Cdata) immutable?

(set_field is as defined in cmmgen.ml)

Thank you!